Explosive composition



' der.

2,918,362 Patented Dec. 2 2, i959 EXPLOSIV E COMPOSITION Duncan P.MacDougall, Pittsburgh, Pa., Paul M. ljye,

Woods Hole, Mass., and George B. Kistiakowsky, Pittsburgh, Pa.,assignors to the United States of America as represented by theSecretary of the Navy No Drawing. Application June 24, 1944' Serial No.542,008 a 1 Claim. c1. 52-6) This invention relates to explosives andhas particular relation to an explosive composition of high density foruse in ordnance devices, such as depth charges, mines, and the like,where high density is one of the desired characteristics of theexplosive.

An object of this invention is to provide an explosive composition whichwill have a high density, an increased damage range as compared to knownexplosives such as trinitrotoluene, and good casting properties.

Another object of the invention is to provide an explosive compositionwhich will have desirable thermostability and an impact sensitivity inthe neighborhood of that possessed by trinitrotoluene.

A further object of the invention is to provide an explosive compositionwhich will be fluid enough to be readily poured at temperatures of about80 to 90 C. but will not be so fluid as to cause serious segregation ofthe components.

Still another object of the invention is to provide an explosivecomposition which will solidify on cooling to give a solid having aconsistent density throughout its mass.

A still further object of the invention is to provide an explosivecomposition which is capable of being safely and efliciently melted,cast and subsequently handled by methods now used for trinitrotolueneand other known explosives.

A still further object of the invention is to provide an explosivecomposition which may be safely and efficiently used in place oftrinitrotoluene and other known military explosives in ordnanceequipment, such as depth charges, mines, and the like.

An additional object of the invention is to provide an explosivecomposition which may be subjected to existing military and navalpractices for handling and firing explosives.

These and other objects of the invention will be better understood byreference to the accompanying description.

The invention broadly comprises an explosive composition oftrinitrotoluene, barium nitrate and aluminum powder. 'In a preferredform, the new explosive composition comprises a composition of 35percent trinitrotoluene, 50 percent barium nitrate and 15 percentaluminum pow- It will be understood that other substantial percentagesof these ingredients may be employed. For example, the composition mayinclude from 15 to 50 percent tn'nitrotoluene, 30 to 60 percent bariumnitrate and about 10 to 25 percent aluminum powder.

An explosive having a high density is particularly desirable for use inunderwater ordnance devices, such as depth charges, mines, and the like,where the function of the ordnance is partially dependent upon itsdegree of buoyancy. For example, the rate of sinking of a depth chargeis primarily dependent upon its density. Although the weight of theordnance devices may be increased by the addition of heavy weights, suchaddition lessens the volume of space which may be allotted to theexplosives. Accordingly,,it is desirable that an explosive compositionbe utilized which will contribute to the weight, and therefore thedensity, of the ordnance equipment for underwater use.

Example 1 A technical grade barium nitrate powder was selected having anapproximate screen analysis as follows: 53 percent through a 325 meshscreen; 20 percent through a 200 mesh screen onto a 325 mesh screen; 11percent through a 150 mesh screen onto a 200 mesh screen; 7 percentthrough a mesh screen onto a 150 mesh screen; and 9 percent through ascreen-slightly coarser than 100 mesh. An atomized aluminum powder wasselected, approximately 95 percent of which was capable of being passedthrough a 200 mesh screen. The particular aluminum powder used in thisexmaple was commercial grade MD 101. An ordinary military grade ofgranular trinitrotoluene was used. These ingredients were compoundedinto a composition comprising 35 percent trinitrotoluene, 50 percentbarium nitrate, and 15 percent of the aluminum powder. It has been foundthat this preferred percentage composition results in an explosivecomposition having desirable characteristics including high density,increased damage range and good casting properties.

The new explosive composition was tested for thermostability by heating10 to 20 gram samples up to 200 C. for 20 minute periods. These samplesfailed to ignite nor was there any visible evidence of decomposition.Further samples were held for a period of two hours at temperaturesbetween 150 C. and 200 C. without any indication of decomposition havingtaken place. Other samples exposed to the standard C. thermostabilitytest for a period of five hours showed no acidity, explosion or otherevidence of decomposition. Other samples exposed to the vacuum stabilitytest showed results approximately the same as those obtained withtrinitrotoluene, while still other samples of the new explosivecomposition were subjected to the standard Woods-metal bath explosiontest and gave no indication of exploding at 360 C.

It is difiicult to compare the sensitivity of a mechanical explosivecomposition with that of a pure explosive material. However, when thenew explosive composition was subjected to tests on standard impactmachines, the tests indicated an impact sensitivity not appreciablygreater than that exhibited by trinitrotoluene. When exposed to thestandard rifle bullet test, the new explosive composition gave someevidence of partial detonation when cast in either a welded steel caseor in standard plumbing pipe nipples.

The new explosive composition solidified on cooling from the moltenstate to give a slightly porous, rock-like material having a density ofabout 2.3 grams per ml. A cast charge of the new explosive compositionwas separated into various small sections which were measured fordensity. It was observed that there was no marked variation in densitybetween the small sections, which indicated that very little settlingtook place either prior to or during solidification of the cast charge.

The physical characteristics of the new explosive composition are suchthat it may be readily substituted for present explosives now used inunderwater ordnance equipment. Thus, the new explosive composition maybe subjected to present loading conditions and practices, it may beshipped and stored by present practices, and it may be detonated bymeans of detonators now in use. In this connection, it 'has been foundthat the new explosive composition is fiuid enough to be readily pouredwhen heated at temperatures from 80 to 90 C., but

it is not so fluid as to cause serious segregation between thecomponents of the composition.

We claim:

A cast explosive composition for underwater ordnance characterized by adensity of substantially 2.3 and consisting essentially of thefollowing, by weight: 35 percent trinitrotoluene, 50 percent bariumnitrate powder of 5 3 percent 325 mesh screen particle size, 20 percent200 mesh screen particle size, 11 percent 150 mesh screen particle size,7 percent 100 mesh screen particle size and 9 percent of particle sizecoarser than 100 mesh screen; and 15 percent atomized aluminum powder,approximately 95 percent of which is of particle size finer than 200mesh screen.

References Cited in the file of this patent UNITED STATES PATENTS

